1. Field of the Invention
The present invention relates to binoculars, and, more particularly, binoculars having a lens barrier for protecting an optical lens.
2. Description of the Related Art
The human eye spacing, namely, the human interpupillary distance varies considerably, depending on age, sex, and from person to person. To cope with this variation, Japanese Unexamined Patent Publication No. 836135 discloses binoculars having a mechanism that adjusts the distance between a pair of lens barrels to accommodate users having a wide range of the inter-pupillary distance.
The binoculars disclosed in Japanese Unexamined Patent Publication No. 836135 drives a lens barrier interlocked with the barrel spacing adjustment. The lens barrier substitutes for conventional lens caps, and serves as a protector for an objective lens unit and an eyepiece lens unit. The barrier mechanism is placed at a position to cover and protect the objective lens unit and the eyepiece lens unit when the binoculars are in their closed position. When the binoculars are in use and are adjusted to an appropriate eye spacing, the lens barrier is retracted along with the adjustment for eye spacing.
Binoculars of well-known types have, between a pair of barrels, an axis about which the barrels are pivoted to adjust the eye spacing.
Since eye-spacing adjustable binoculars such as these typically provide the capability to displace the pair of barrels relative to one another, the binoculars are closed with the barrel spacing narrowed, and are set up for use with the barrel spacing widened and then adjusted for eye spacing.
In the binoculars disclosed in Japanese Unexamined Patent Publication No. 836135, however, the lens barrier is moved in an optical system of objective lens and eyepiece lens along with the barrel spacing adjustment. The lens barrier partly remains in the optical system with the lens barrier set in the vicinity of a minimum eye spacing position in an eye spacing adjustment region. With the lens barrier at the minimum eye spacing position, the image is subject to a light quantity drop and shading.
It is a first object of the present invention to provide binoculars that are set to an operational state with a simple operation during use while reliably carrying out its lens protection function in its closed state.
It is a second object of the present invention to provide binoculars that are free from any droop in light quantity and image shading during use.
The binoculars of the present invention include a pair of lens barrels, each lens having an optical system, a relative movement between the lens barrels causing the lens barrels to be displaced relative to each other so as to travel between a closed state and an operational state in which an eye spacing adjustment is enabled, a barrier that is moved between an optical system protective position with the lens barrels in the closed state and a retracted position with the lens barrels in the operational state; and a barrier control member mounted on the lens barrels and which moves the barrier from the optical system protective position to the retracted position in response to the displacement of the lens barrels from the closed state to the operational state.
These objects and advantages of the present invention will become further apparent from the following detailed explanation.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.